This study assesses the influence of a hypertonic glucose infusion induced facial fluch on ear and facial temperatures in normal subjects, migraineurs, and subjects with cluster headache. Correlations between temperature changes, symptomatic facial flushing, blood glucose, insulin, and beta-endorphin levels will be made to assess the significance of blanching (drop in skin temperature) in migrainers, and flushing (rises in skin temperature in patients with cluster headache.